# Rendered by the nginx-unprivileged entrypoint: envsubst expands ${API_UPSTREAM}
# (and only names that exist in the environment — nginx's own $uri/$host/etc.
# are left alone) into /etc/nginx/conf.d/default.conf at container start.

server {
    # 8080, not 80: unprivileged nginx runs as uid 101 and cannot bind <1024.
    listen       8080;
    listen       [::]:8080;
    server_name  _;

    root  /usr/share/nginx/html;
    index index.html;

    # The bundle is already gzipped over the wire by this; Brotli would need a
    # module the stock image does not carry, so gzip it is.
    gzip              on;
    gzip_vary         on;
    gzip_min_length   1024;
    gzip_proxied      any;
    gzip_types        text/plain text/css application/javascript application/json
                      image/svg+xml application/manifest+json;

    server_tokens off;

    # nginx does NOT merge add_header across levels: if a location block adds
    # even one add_header of its own, every add_header set here at server
    # level is discarded for responses from that location — not appended to.
    # /assets/, /fonts/ and = /index.html below each set their own
    # Cache-Control, so the four security headers are repeated verbatim
    # inside each of those blocks. Add a header here, and it must be added
    # there too (or it silently never reaches those responses).
    add_header X-Content-Type-Options nosniff       always;
    add_header X-Frame-Options        DENY          always;
    add_header Referrer-Policy        no-referrer   always;

    # Derived from the actual production build (frontend/dist): no inline
    # <script>/<style>, all JS/CSS/fonts same-origin, the only data: URIs are
    # an <img> (QR code) and a CSS background-image (chevron icon) — hence
    # img-src needs data: but nothing else does. API is same-origin /api/.
    add_header Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self'; img-src 'self' data:; font-src 'self'; connect-src 'self'; object-src 'none'; base-uri 'self'; form-action 'self'; frame-ancestors 'none'" always;

    # Container-level liveness. Served from memory, so a broken bundle or a
    # read-only mount cannot make this lie.
    location = /healthz {
        access_log off;
        # default_type, not `add_header Content-Type`: add_header appends, so
        # the response would carry two Content-Type headers.
        default_type text/plain;
        return 200 "ok\n";
    }

    # Same-origin API. Because the browser only ever talks to this origin, the
    # backend's CORS allow-list is not exercised at all in this deployment.
    location /api/ {
        proxy_pass              ${API_UPSTREAM};
        proxy_http_version      1.1;
        proxy_set_header Host              $host;
        proxy_set_header X-Real-IP         $remote_addr;
        proxy_set_header X-Forwarded-For   $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_set_header Connection        "";

        # The FK-scraper poll endpoints are long-ish; don't cut them at 60s.
        proxy_read_timeout 120s;
        proxy_buffering    off;
    }

    # Vite emits content-hashed filenames under /assets, so they are immutable.
    location /assets/ {
        access_log off;
        # `expires 1y` would emit its own Cache-Control alongside this one;
        # one explicit header is clearer than two contradicting-looking ones.
        add_header Cache-Control "public, max-age=31536000, immutable" always;
        # Repeated: see the server-level comment above — an add_header here
        # discards the server block's add_headers for this location.
        add_header X-Content-Type-Options nosniff       always;
        add_header X-Frame-Options        DENY          always;
        add_header Referrer-Policy        no-referrer   always;
        add_header Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self'; img-src 'self' data:; font-src 'self'; connect-src 'self'; object-src 'none'; base-uri 'self'; form-action 'self'; frame-ancestors 'none'" always;
        try_files  $uri =404;
    }

    # Self-hosted webfonts are versioned in their filename (…-v7.woff2), so
    # a glyph update ships as a new file and the old one can be cached forever.
    location /fonts/ {
        access_log off;
        add_header Cache-Control "public, max-age=31536000, immutable" always;
        # Repeated: see the server-level comment above.
        add_header X-Content-Type-Options nosniff       always;
        add_header X-Frame-Options        DENY          always;
        add_header Referrer-Policy        no-referrer   always;
        add_header Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self'; img-src 'self' data:; font-src 'self'; connect-src 'self'; object-src 'none'; base-uri 'self'; form-action 'self'; frame-ancestors 'none'" always;
        try_files  $uri =404;
    }

    # index.html is the only mutable entry point — never cache it, or a deploy
    # leaves clients pinned to a stale asset graph.
    location = /index.html {
        add_header Cache-Control "no-cache" always;
        # Repeated: see the server-level comment above — this is the response
        # the CSP/X-Frame-Options/etc. exist to protect, so it must not lose
        # them just because this block also sets Cache-Control.
        add_header X-Content-Type-Options nosniff       always;
        add_header X-Frame-Options        DENY          always;
        add_header Referrer-Policy        no-referrer   always;
        add_header Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self'; img-src 'self' data:; font-src 'self'; connect-src 'self'; object-src 'none'; base-uri 'self'; form-action 'self'; frame-ancestors 'none'" always;
    }

    # SPA fallback. react-router-dom uses BrowserRouter, so a hard refresh or a
    # shared link on a client-only route (/calendar, /settings, ...) arrives
    # here as a real HTTP request for a path with no file behind it. Without
    # this line that is a 404 and client-side routing breaks on reload.
    location / {
        try_files $uri $uri/ /index.html;
    }
}